Learn about this topic in these articles:

characteristics

Erythema nodosum is a hypersensitivity reaction most commonly associated with streptococcal infection, drugs (particularly oral contraceptives), and sarcoidosis (a systemic disease characterized by the formation of granulation, or scarlike, tissue). It is marked by the sudden onset of multiple, red, painful nodules in the deeper layer of the skin on the external surface of the lower legs. It...

Several types of arthritis appear to be related to a hypersensitivity reaction. Erythema nodosum is a skin disease characterized by the formation of reddened nodules usually on the front of the legs. In the majority of cases, pain may arise in various joints, and sometimes swelling appears. Lymph nodes at the hilus of the lung (the site of entrance of bronchus, blood vessels, and nerves) are...

yersiniosis

...gastrointestinal infection caused by the bacterium
Yersinia enterocolitica, characterized by fever, often-bloody diarrhea, and abdominal pain. A temporary rash called
erythema nodosum also may appear on the skin, and the disease can lead to a temporary arthritis of the knees, ankles, or wrists. Frequently occurring in young children, the infection is more common...

Our new Britannica Explores newsletter has all the latest stories along with other great content.
Answering nagging questions like “Is zero an odd or even number?” and others!
Still curious? Sign up here to get Britannica Explores delivered right to your inbox!

Thank you for subscribing!

Be on the look out for the Britannica Explores newsletter to deliver more Demystified stories right to your inbox.